THE OLFACTORY NERVE OF LEPIDOSTEUS 127 



lage medianly. It appears to be almost distinct from the olfactory 

 nerve by reason of a weak investing membrane. Dorso-lateral 

 to the olfactory nerve is a medullated nerve which is probably the 

 ophthalmic branch of the V and MI cranial nerves. It may 

 be significant that the central ganglion of the nervus terminalis 

 is located not far from the place where the ophthalmic ramus 

 joins the olfactory nerve on its way forward. This would provide 

 connection posteriorly with the sympathetic system, if such a 

 connection exists. The ophthalmic ramus runs parallel with 

 the olfactory in close juxtaposition as far forward as the olfactory 

 capsules. This transverse series is so defective in the region near 

 the olfactory capsules that no peripheral ganglia were found on 

 either side. 



When the adult fishes were examined, the central and periph- 

 eral ganglia of the nervus terminalis were found to occupy the 

 same relative positions as in the young fishes of 90 and 125 mm. 

 length, just described. The central ganglion is generally found 

 about 25 mm. rostral of the brain, immediately anterior to the 

 masticating muscles. It has a' ventral position on the olfactory 

 nerve near the blood vessels. Figure 16 would serve to represent 

 a cross-section of the adult, if the ophthalmic ramus were moved 

 \'entrally and laterally and the olfactory nerve were made larger. 

 The ganglion contains not over two hundred cells. Search was 

 made for any connection of the nervus terminalis with other 

 nerves of the head. The ophthalmic branch already mentioned 

 is compacted within the same bone-covered channel so that to 

 the naked eye the olfactory nerve and the ophthalmic seem to 

 l)e in contact. In sections of the adult the distance of the oph- 

 thalmic ramus from the ganglion of the nervus terminalis is 1 mm. 

 In vom Rath preparations of the adult a slender nerve, of medul- 

 lated fibers for the most part, was found in contact with the ol- 

 factory nerve at a point where there were five or six large ganglion 

 cells. Whether these were outlying cells of the central ganglion 

 of the nervus terminalis could not be established with certainty. 



It has been impracticable to search the whole length of the 

 olfactorj^ nerve of the adult fish for ganglion cells, but we have 

 examined the nasal capsules. In some cases no peripheral gan- 



